CH. Ill] REPTILES AND OCEAN BARRIERS. 149 



marine strata, which in all probability indicates that they 

 were at least frequently in the habit of swimming out to 

 sea. It is not of course positive proof, for it might be 

 urged that we have to do merely with the remains of 

 crocodiles which had been washed down the rivers after 

 death. The interesting point in connection with these 

 habits of the more ancient crocodiles is that many living 

 crocodiles will take to the sea sometimes ; a crocodile has 

 been met with at a very long distance from land — within 

 the last year or two a crocodile has been recorded at the 

 Cocos Islands, which must therefore have swum for a con- 

 siderable distance. 



Not only are there purely marine snakes, like the 

 poisonous Pelamys, but serpents which are habitually 

 terrestrial will make an occasional trip to sea. It is 

 stated the snake Tropidonotus tessellatus (allied to our 

 common Grass snake) which lives upon the shores of 

 Dalmatia will enter the sea. Even the cobra (Naia 

 tripudians) has been captured entangled in the anchor 

 chain of a ship 1 . Fresh water tortoises are by no means 

 always impatient of salt water. And finally as many 

 lizards and probably all snakes can swim in fresh water it 

 is quite a reasonable supposition that in some cases they 

 could survive a sea voyage. 



With these examples before us it is clearly, incorrect 

 to say that lizards and serpents are incapable of passing 

 ocean barriers, which indeed their presence on oceanic 

 islands shows conclusively that they can do. Mr Wallace 

 while admitting that lizards possess some means of 

 1 Cf. Simroth, Die Entstehung der Landthierr.. 



